A method of making a microelectronic assembly includes providing a first microelectronic element and a second microelectronic element with confronting, spaced-apart surfaces defining a space therebetween and providing one or more masses of a fusible conductive material having a melting temperature below about 150° C. in said space, whereby the fusible conductive masses connect the first and second microelectronic elements to one another. Next, a flowable material is introduced between the confronting surfaces of the first and second microelectronic elements and around the one or more fusible conductive masses and the flowable material is then cured to provide a compliant layer disposed between said confronting surfaces and intimately surrounding each fusible conductive mass. The fusible conductive masses are capable of electrically interconnecting the contacts on microelectronic elements confronting one another and/or conducting heat between confronting microelectronic elements.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A microelectronic package comprising: (a) a first microelectronic element having a front surface including contacts and a rear surface, said first microelectronic element being operable in a range of operating temperatures; (b) a package element having a surface confronting the rear surface of said microelectronic element; (c) a first layer of a compliant material having top and bottom surfaces extending in lateral directions between said confronting surfaces of said first microelectronic element and said package element; (d) one or more masses of a thermally conductive material dispersed in said first compliant layer so that said thermally conductive masses are spaced apart from one another in lateral directions, said thermally conductive masses having a melting temperature within or below the range of operating temperatures of said first microelectronic element, each said thermally conductive mass being adjacent to said confronting surfaces of said first microelectronic element and said package element for transferring heat therebetween during operation of said first microelectronic element; and (e) a second microelectronic element overlying said front surface of said first microelectronic element so that said first microelectronic element is disposed between said package element and said second microelectronic element, said second microelectronic element being electrically connected to said first microelectronic element.
2. A package as claimed in claim 1 , wherein said second microelectronic element has a contact bearing surface confronting the contact bearing front surface of said first microelectronic element; , the package further comprising: a second layer of a compliant material having top and bottom surfaces extending in lateral directions between said confronting surfaces of said first and second microelectronic elements; one or more masses of a fusible electrically conductive material dispersed in said second compliant layer so that said electrically conductive masses are spaced apart from one another and extend between contacts of said first and second microelectronic elements, said electrically conductive masses having a melting temperature within or below said range of operating temperatures.
3. A package as claimed in claim 2 , wherein said first and second compliant layers are contiguous with one another.
4. A package as claimed in claim 2 , wherein said thermally conductive material and said electrically conductive material comprise one or more metals.
5. A package as claimed in claim 1 , wherein said second microelectronic element includes a flexible dielectric sheet having a first surface confronting the contact bearing front surface of said first microelectronic element and a second surface facing away from said first microelectronic element, said flexible dielectric sheet including conductive terminals and accessible at said second surface, the package further comprising flexible leads electrically connected between said conductive terminals said contacts of said first microelectronic element for electrically interconnecting said first and second microelectronic elements.
6. A package as claimed in claim 5 further comprising: a second layer of a compliant material having top and bottom surfaces extending in lateral directions between said confronting surfaces of said first and second microelectronic elements; one or more masses of a thermally conductive fusible material dispersed in said second compliant layer so that said thermally conductive masses are spaced apart from one another in lateral directions, said thermally conductive masses having a melting temperature within or below the range of operating temperatures of said first and second microelectronic elements, each said mass of thermally conductive material having opposite ends adjacent to said confronting surfaces of said first and second microelectronic elements for conducting heat therebetween.
7. A package as claimed in claim 1 , wherein said first microelectronic element includes one or more semiconductor chips.
8. A package as claimed in claim 1 , wherein said package element includes a heat sink.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
January 10, 2001
August 20, 2002
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